Microwave ovens usually comprise a cooking chamber (or cavity) in which a load, such as a food item, is placed to be heated, a microwave generator for generating microwaves and a transmission line for transmitting the microwaves to the cavity. A common problem associated with prior art microwave ovens is that the heating provided by the microwaves is not always suitable for the particular food item placed in the cavity. For example, the heating may result in hot and cold regions in the food item, leaving the user with the choice of accepting that some regions of the food item are not heated properly or continuing the heating process and thereby running the risk of burning parts of the food item.
A possibility to overcome the above-mentioned problem is to equip the microwave oven with sensors for monitoring the cavity and the load in order to determine how to heat the load. However, such sensors do not provide sufficient information about the load to provide efficient heating. Infrared sensors for example may be used to monitor the surface of the load, but provide little or no information about the interior of the load, its cooking state or its total weight.
Thus it would be desirable to provide a microwave heating apparatus and a method for heating a load by means of microwaves with an alternative way of monitoring the load in order to improve the efficiency of the heating process.